Repeater systems are used to provide communication coverage to a substantially wide area. A repeater system may include two or more repeaters, wherein each repeater covers a portion of the coverage area. Each repeater includes a receiver which receive a radio frequency (RF) received signal from a portable or mobile communication unit on an inbound channel, and a transmitter which repeats (or retransmits) the received signal on an outbound channel. However, it two or more repeaters transmit the repeated signal simultaneously (simulcast), transmission collisions may occur causing the repeated signal to become distorted.
In a conventional repeater system simulcast is avoided by activating only a desired repeater in the system. The desired repeater is activated via a unique preamble or private line (PL) code. The received signal is modulated by a PL code, and activates a particular repeater in the system. However, a user must know the location of each repeater and activates a correct repeater as he travels around the coverage area. The activation of a desired repeater may be accomplished by slaving multiple PL codes to the inbound channel and providing a switch on the communication unit to select the desired PL code. The user by switching the PL codes activates different repeaters. This method is undisired, because it requires user intelligence for knowing the repeater location and user interaction for manually switching the PL codes.
Another wide area coverage system may include geopraphically distributed remote receivers, a public switching telephone network (PSTN), and a central transmitter. The satellite receivers receive the received signal and route it to the PSTN through telephone landlines. A voting means selects the best received signal based on a predetermined signal quality characteristic, such as signal to noise ratio, and routes the received signal to a single central transmitter for retransmission. The central transmitter is a substantially high power transmitter and covers the coverage area. In this system user's manual interaction is not required, and the system provides repeater intelligence,. However, this system is costly and complicated and requires utilization of dedicated landlines.